Another fuel pump question

Post by **Sidney'61** » Mon Jul 13, 2009 11:13 pm

I took the pump of the car as it simply stopped pumping, when it is not connected to the car and just wired up to a battery it ticks away happily, then when connected to the car but with out the hose connected it will pump fuel and squirt it out of the top but once the fuel hose is connected it will stop pumping completely. I assume it just hasn't got enough power to deal with the pressure, is this sorted by adjusting the points? if so, how?

Thanks

Post by **Peetee** » Tue Jul 14, 2009 7:46 am

I assume it just hasn't got enough power to deal with the pressure, is this sorted by adjusting the points? if so, how?

Mine was adjusted, dismantled and adjusted again over several days and ruined journeys. Eventually it would cope with tickover but nothing more.
In the end I had to get a new pump.
Now it's ticking loudly so I'm going to reverse flush the fuel line just to be sure.

Post by **bmcecosse** » Tue Jul 14, 2009 8:32 am

The pump is supposed to stop when the float chamber is full of petrol. Is this what's happening ? If you run the engine - does it start ticking again to keep up ?

Post by **alex_holden** » Tue Jul 14, 2009 9:06 am

On one of my spare pumps I've had problems with the (new replacement) diaphragm sticking where it slides inside the casing. It will pump OK with nothing connected, then if you put your thumb over the outlet it jams and stops pumping until you give it a thump to get it going again. I managed to improve but not completely cure it by sanding a bit off the outside of the plastic spacer (early pumps had a set of steel 'donuts' instead). That pump's sat in a spares box in the garage waiting for me to collect enough Round Tuits to have another go with it.

Post by **Peetee** » Tue Jul 14, 2009 10:33 am

That pump's sat in a spares box in the garage waiting for me to collect enough Round Tuits to have another go with it

And mine's still on the car waiting for me to do the same!
That's it I'm signing out and scuttling round to the garage.

Post by **maroon** » Sat Jul 25, 2009 11:10 am

i found a very usefull video on youtube theres a man shows you how to strip a su pump change the points and set the dierfram

Post by **bmcecosse** » Sat Jul 25, 2009 11:43 am

Post up the link!

Post by **rayofleamington** » Sat Jul 25, 2009 12:20 pm

Andy - I'm presuming you mean it won't pump even when the carb is empty! If it stops pumping only when carb is full, then it's fixed!

If it pumps off the car, it's unlikely to be the points - the solenoid loads the diaphragm againsty a spring. The diaphragm returns when the fuel is released and that resets the points.
If the small back pressure of connecting the fuel hose to an empty carb is enough to stop it, then the diaphragm is not returning properly under spring load. If it goes 'nearly all the way' then adjusting the points may help, but I don't think that's the problem as it works off the carb.